It’s time to squash that age-old myth: Your period doesn’t protect you from pregnancy. There are a couple of reasons why. First, some women may bleed when their ovaries release an egg each month, called ovulation, and mistake it for their period. You’re at your peak fertility when you ovulate, so if you have sex during this time, it could actually make you more likely to get pregnant.
Second, you may ovulate before your period is over or within a few days after the bleeding stops. Since sperm can hang out in your body for up to 3 days, having sex during your period could lead to conception.
Use a condom or other form of birth control to prevent an unplanned pregnancy, no matter what time of the month it is.